Treatment in an automatic clothes dryer has been shown to be an effective means for imparting desirable tactile properties to fabrics. For example, it is becoming common to soften fabrics in an automatic clothes dryer rather than during the rinse cycle of a laundering operation. (See U.S. Pat. No. 3,442,692, Gaiser, issued May 6, 1969.)
Fabric "softness" is an expression well defined in the art and is usually understood to be that quality of the treated fabric whereby its handle or texture is smooth, pliable and fluffy to the touch. Various chemical compounds have long been known to possess the ability to soften fabrics when applied to them during a laundering operation.
The term fabric "softness" also connotes the absence of static "cling" in the fabrics, and the community used cationic fabric softeners provide both softening and antistatic benefits when applied to fabrics. Indeed, with fabrics such as nylon and polyester, the user is more able to perceive and appreciate an antistatic benefit than a true softening benefit.
On the other hand, soil release treatment of fabrics in an automatic clothes dryer is not as common as softening treatment.
U.S. Pat. No. 4,238,531, Rudy et al., issued Dec. 9, 1980, discloses in its Examples 8 and 9 a soil release agent adjuvant plus a "distributing aid," polyethylene glycol (PEG). The key combination of fabric softening plus soil release treatment in one automatic clothes dryer product is not disclosed in Rudy et al.
An improved dryer-added fabric conditioning article containing a mixture of a fabric softening agent and a polymeric soil release agent impregnated on a flexible substrate is disclosed in U.S. Pat. No. 4,749,596, M. D. Evans et al., issued June 7, 1988; said patent is incorporated herein by reference. This article provides soil release and fabric softening benefits for use in automatic dryers.
It was found, however, that the mixing of polyoxyethylene terephthalate soil release polymers, particularly those of higher molecular weights or higher viscosities, with the fabric softening agent did not occur except with vigorous agitation. When agitation ceased, phase separation occurred readily. An additional problem associated with the use of a nonhomogenous mixture is the separation of actives at the point of application of the active mixture on the substrate resulting in unevenly impregnated sheets.
It is therefore an object of the present invention to provide a stable and initimately mixed, homogenous fabric conditioning composition containing polyoxyethylene terephthalate soil release polymer and fabric softening agent. Another object of the present invention is to provide a homogenous and stable composition containing said soil release polymer and fabric softening agent, said actives do not separate at the point of impregnation on the flexible substrate sheet. It is a further object of the present invention to provide articles in which the substrate sheets are coated evenly and uniformly with the conditioning actives. It is yet another object herein to provide articles which can be added to an automatic clothes dryer to provide fabric soil releasing plus softening benefits to the washed laundry. And it is an object of the invention to provide methods for conditioning fabrics.
These and other objects will become obvious from the following disclosure.